Blood pressure long term regulation: A neural network model of the set point development

Abstract

BackgroundThe notion of the nucleus tractus solitarius (NTS) as a comparator evaluating the error signal between its rostral neural structures (RNS) and the cardiovascular receptor afferents into it has been recently presented. From this perspective, stress can cause hypertension via set point changes, so offering an answer to an old question. Even though the local blood flow to tissues is influenced by circulating vasoactive hormones and also by local factors, there is yet significant sympathetic control. It is well established that the state of maturation of sympathetic innervation of blood vessels at birth varies across animal species and it takes place mostly during the postnatal period. During ontogeny, chemoreceptors are functional; they discharge when the partial pressures of oxygen and carbon dioxide in the arterial blood are not normal.MethodsThe model is a simple biological plausible adaptative neural network to simulate the development of the sympathetic nervous control. It is hypothesized that during ontogeny, from the RNS afferents to the NTS, the optimal level of each sympathetic efferent discharge is learned through the chemoreceptors' feedback. Its mean discharge leads to normal oxygen and carbon dioxide levels in each tissue. Thus, the sympathetic efferent discharge sets at the optimal level if, despite maximal drift, the local blood flow is compensated for by autoregulation. Such optimal level produces minimum chemoreceptor output, which must be maintained by the nervous system. Since blood flow is controlled by arterial blood pressure, the long-term mean level is stabilized to regulate oxygen and carbon dioxide levels. After development, the cardiopulmonary reflexes play an important role in controlling efferent sympathetic nerve activity to the kidneys and modulating sodium and water excretion.ResultsStarting from fixed RNS afferents to the NTS and random synaptic weight values, the sympathetic efferents converged to the optimal values. When learning was completed, the output from the chemoreceptors became zero because the sympathetic efferents led to normal partial pressures of oxygen and carbon dioxide.ConclusionsWe introduce here a simple simulating computational theory to study, from a neurophysiologic point of view, the sympathetic development of cardiovascular regulation due to feedback signals sent off by cardiovascular receptors. The model simulates, too, how the NTS, as emergent property, acts as a comparator and how its rostral afferents behave as set point.

Medical informatics research trend analysis: A text mining approach

“…Included examples are blood pressure long-term regulation, oscillometric measurement of systolic and diastolic blood pressures, a procedure for the evaluation of non-invasive blood pressure simulators, neural set points for the control of arterial pressure, the estimation of mean arterial pressure from the oscillometric cuff pressure, and the feasibility of measuring coronary blood flow. 31–36…”

“…Included examples are blood pressure long-term regulation, oscillometric measurement of systolic and diastolic blood pressures, a procedure for the evaluation of non-invasive blood pressure simulators, neural set points for the control of arterial pressure, the estimation of mean arterial pressure from the oscillometric cuff pressure, and the feasibility of measuring coronary blood flow. [31][32][33][34][35][36] The term "image" is mainly used in the context of guiding treatments. Some examples include image-guided oral implantology, design of the image-guided biopsy marking system for gastroscopy, extraction of three-dimensional (3D) information on bone remodeling in the proximity of titanium implants in SRmuCT image volumes, 3D patient-specific geometry of the muscles involved in knee motion from selected magnetic resonance imaging (MRI) images, and jaw tissues segmentation in dental 3D computed tomography (CT) images using fuzzy-connectedness and morphological processing.…”

Conditional viral tracing reveals that steroidogenic factor 1‐positive neurons of the dorsomedial subdivision of the ventromedial hypothalamus project to autonomic centers of the hypothalamus and hindbrain

“…This suggests that VMH efferents within the NTS are not concerned with taste (Chen and Di Lorenzo, 2008), but instead contribute to autonomic and sympathetic functions. Specifically, caudal regions of the NTS are principally concerned with tonic autonomic regulation of blood pressure (Massari et al, 1998;Thrasher, 2004;Zanutto et al, 2011). Importantly, VMH activity has been shown to influence cardiovascular function.…”

Coherence: A Novel Nonpharmacological Modality for Lowering Blood Pressure in Hypertensive Patients

“…Recent findings confirm that there is indeed a set-point for mean long-term BP that is regulated by the nervous system rather than the generally accepted model that the renal output curve determines the set-point for long-term arterial BP regulation. Osborn has provided compelling arguments for a central nervous system–based set-point for long-term arterial BP 56 and in recent articles by Zanuto et al, 57 , 58 it was shown that when all of the cardiovascular receptors (baro-, chemo-, and cardiopulmonary) are deinnervated, sustained hypertension results. Zanuto has also provided evidence that nucleus tractus solitarius acts as a compactor and controls the set-point for mean atrial BP, which is consistent with Pribram's model.…”